Just make the things run on some "renewable" fuel like ethanol or RME and that whole carbon thing can be relegated to the sideline. If/when it comes that far it

Just make the things run on some "renewable" fuel like ethanol or RME and that whole carbon thing can be relegated to the sideline. If/when it comes that far it'll probably be more expensive to run these cars but given that the clientele is not that price-conscious that should not be a problem. While it is not really feasible to produce enough ethanol to run the entire ICE fleet it should not be any problem to produce enough for a limited number of "exemption" vehicles. Included in that list can be classic cars, many of which were built to be able to use multiple fuels anyway - e.g. a Model T or Model A Ford can run on ethanol straight from the factory by adjusting the mixture (which is a standard part of operating such a vehicle anyway). Ethanol has a high octane number and as such is useable for high-compression engines like those in "supercars". Fuel consumption will go up but the clientele does not care about such trivialities. Converting petrol engines to ethanol is a simple task so Ferrari (et al) should not have any problems doing such.